(E)-8-(3,4-dimethoxystyryl)-1,3-diethyl-7-methyl-3,7-dihydro-1H-purine-2,6-dione or a pharmaceutically acceptable salt thereof are known to show an adenosine A2A receptor antagonistic activity and be useful as a therapeutic agent for depression and the like (Japanese Patent No. 2928386).
Furthermore, pharmaceutical compositions which comprise a non-xanthine derivative having an adenosine A2A receptor antagonistic activity and an antidepressant drug are known (WO 03/022283).
On the other hand, a treatment of depression carried out by an administration of a tricyclic antidepressant, a tetracyclic antidepressant, a selective serotonin reuptake inhibitor, a selective noradrenalin reuptake inhibitor, a dopamine reuptake inhibitor, a serotonin-noradrenalin reuptake inhibitor or the like, or by an administration in combination of these. However, these administrations involve medical problems of side effects such as side effects on an autonomic nervous system, cardiotoxicity, side effects on a digestive system (for example, nausea, anorexia, loose stool, diarrhea and the like), sexual dysfunctions, withdrawal syndrome, extrapyramidal disorders, serotonin syndrome, weight loss, anxiety and impatience, syndrome of inappropriate antidiuretic hormone in the aged, urinary retention, dysuria, a rash, headache and palpitation [Pharmacia, 38, 737-742, (2001)]. Furthermore, treatment of depression is carried out by an administration of a monoamine oxidase inhibitor. However, the administration also involves medical problems of side effects such as serious hepatic function disorder and rise of blood pressure [Pharmacia, 38, 737-742 (2001)].